Question

Numbers 1 to 20 are placed in a bag. Without replacing the first number, what is the probability that the first number drawn will be odd and the second number be even?

Answer 1

• 5/19 or 26.3%

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There are total 20 numbers and half of them odd and half of them even.

Without replacement, the probability of an odd and then even number is:

• P(odd then even) = P(odd) * P(even)
• P(odd then even) = 10/20 * 10/(20 - 1)
• P(odd then even) =1/2 * 10/19
• P(odd then even) = 5/19 or 26.3%